Study on the relationship between rainfall characters and runoff-sediment yield of slopes of different land use types in northern mountain area of Hebei

A study was made in the highly fragile ecological environment with serious soil and water loss in northern mountain area of Hebei Province,which was the water source area of the cities of Beijing and Tianjin.Three runoff plots with land use types of forest,open forest and natural grassland were constructed in Caojiagou of Weichang County,and the rainfall characters and runoff and sediment yield of the three plots were analyzed.The results showed that the rainfalls which caused runoff on the plots were mainly moderate rain and heavy rain,and the average rainfall intensity was 5.83 mm/h;correlative analysis showed that there was a positive correlation between runoff and the product of rainfall and rainfall duration;the correlation coefficients between sediment yield modules and the product of rainfall and rainfall intensity of forest,open forest and natural grass land were 0.587,0.501 and 0.613 respectively;the sediment yield modules of open forest and natural grass land showed a highly significant correlation with the runoff depth,while the forest′ was not.The capacity of soil and water conservation of the three slopes was in the order of forestnatural grass landopen forest.